The invention relates to a dental laser arrangement switchable between different modes of operation.
Such a dental laser arrangement is already known from WO 98/41355 A (a similar laser arrangement is described in WO 95/32679 A); there, the laser radiation is used for the ablation of hard tooth tissue, and moreover, it is provided to have different laser radiation with different wave lengths for different applications (e.g. surface ablation and in-depth ablation) and, accordingly, different laser sources are to be employed between which it is switched during operation. This use of several laser sources as well as the further provided use—according to WO 98/41355 A—of separate optical fibers for each laser radiation is, however, rather complex.
As such, dental medicine has various possibilities of using lasers. For instance, in addition to the removal of tooth tissue, the sealing of surfaces of hard tissue by means of short laser pulses is conceivable, superheating of the tooth tissue having to be avoided just as during ablation thereof. On the other hand, thermal interactions between laser beam and tissue are conceivable and desired, i.e. in that case when a coagulation of protein is desired for the stopping of bleedings.
As has been mentioned, various laser sources have been used in the past for various treatments in dental medicine, wherein also the changing between these systems is complex, in particular when additional parts, such as manual devices, must be exchanged.
On the other hand, short-pulse laser arrangements are already known with which short laser pulses of high energy are produced in a mode-locked state. Such short-pulse laser arrangements are, e.g., used for the processing of materials or also for scientific projects, and also a use in dental medicine has already been suggested, cf. U.S. Pat. No. 5,742,634 A. As regards the production of short laser pulses, reference may also be made to WO 98/10494 A as well as to A. Stingl et al: Generation of 11-fs pulses from a Ti:sapphire laser without the use of prisms; Optics Letters Vol. 19, No. 3, 1 Feb. 1994, pp. 204–206.
The standard technique for producing short laser pulses of high energy is based on the technique of a laser oscillator and a laser amplifier. The laser oscillator which contains a pump unit to which, e.g., a laser pump beam is supplied, or in which a diode laser is provided, will generate a sequence of short laser pulses of low energy, e.g. with a repetition frequency in the range of some ten MHz. From these oscillator laser pulses, pulses with a lower repetition frequency are selected and amplified in a regenerative or so-called multi-pass amplifier to give pulses of high energy.
What is also known is the so-called “all-in-one” laser concept, in which merely one laser arrangement is provided which is used both as oscillator and also as regenerative amplifier, by simply performing the pulse formation (at low energies), on the one hand, and the amplification (to high energies), on the other hand, at different times. Known laser arrangements of this type (cf. e.g. L. Turi, T. Juhasz: Diode-pumped Nd:YLF all-in-one laser; Optics Letters Vol. 20, No. 14, 15 Jul. 1995, p. 1541–1543), having an oscillator function as well as an amplifier function use active mode-locking with an acousto-optic modulator.
An all-in-one laser modified in relationship to the former is furthermore described in the earlier application WO 01/05001 A (PCT/AT00/00173) which is not a prior publication.